The present disclosure relates to an intake system of an engine.
Japanese Unexamined Patent Application No. 2010-14079 discloses a control device of an internal-combustion engine, and an intake system (i.e., an intake manifold) controlled by the control device. This intake system includes individual intake passageways provided to respective cylinders. Each of the individual intake passageways branches upstream into a first intake passageway and a second intake passageway, and each of the first and second intake passageways communicates with a volume chamber in a surge tank. Meanwhile, the first and second intake passageways of each individual intake passageway converge downstream into one intake passageway. Each of the first and second intake passageways is configured to obtain a dynamic supercharging effect at a different engine revolution. Moreover, a variable valve is provided to a branching point of the first and second intake passageways. This control device continuously changes an opening of the variable valve, based on a running state of the engine, to achieve the dynamic supercharging effects and increase the volumetric efficiency between the vicinity of a first revolution in the middle speed range and the vicinity of a second revolution in the high speed range. Thus, the control device intends to obtain high engine torque.